XVI International Botanical Congess

High levels of species diversity are often attributed to the evolution of a key innovation that allowed the invasion of a new 'adaptive zone'. However, understanding the link between a key innovation and the process of species diversification has been problematic. We have found that the evolution of nectar spurs is correlated with increased species diversity. Spurs may influence species diversity by allowing specialization to different pollinators. Using pollinator choice experiments, phylogenetic reconstruction, hybrid zone analysis and genetic dissection of floral traits, we are determining how changes in floral morphology influence reproductive isolation. Recent studies across hybrid zones of Aquilegia formosa and A. pubescens show that simple changes in floral morphology strongly influence pollinator visitation patterns as well as pollen movement.